1. Field of the Invention:
This invention relates to an ink reservoir or cartridge for attachment to the posterior end of a tubular writing pen by being pushed over the rear end of a cylindrical body. The cylindrical body is hollow for supporting a writing tube at its front end. An ink pressure equalization chamber means is defined within a front wall region of the reservoir cartridge which cooperates with the exterior surface of the hollow body, adjacent the writing tube. The equalization chamber may be covered and sealed by the interior surface of a removable sleeve.
2. Description of the Prior Art:
A known ink reservoir cartridge of this type is illustrated in West German AS No. 19 67 021. Therein, an ink pressure equalization chamber is provided on the exterior surface of the forward end of the pen. The ink pressure equalization chamber is covered by a removable sleeve which threadly engages the cylindrical body, when the ink reservoir cartridge is attached. This removable sleeve is formed as a unitary piece for threaded engagement with the cylindrical body. A connecting bore extends transversely through the removable sleeve and opens directly into the interior chamber of the cylindrical body. The result is an ink pressure equalization chamber, which communicates at its posterior end with the interior chamber of the cylindrical body and its anterior end with ambient air. Accordingly, there is achieved in West German AS No. 19 67 021 a relatively great pressure differential between the anterior end of the writing tube and the transverse connecting bore. This relatively great pressure differential, thusly provided by the equalization chamber, is not optional. Also, the equalization chamber is relatively short and has, therefore, only a relatively limited volume in which to accomodate ink or writing fluid.